I am working on a hexdump library in Python 3.7.4.
Whenever an issue is triggered, the error message shows up. I can usually edit and correct the file(library), but when I reimport the library and rerun the function, it throws the same error on the same line number, even if the line was removed or commented out.

I think this is due to str bytes concatenation error on line number 19. Editing and reimporting doesn't give you new code in repl. Try the changes in new repl after changing it in file. Python will just use unchanged code and will use line number 19 in traceback to show error which is different as file was edited.

Importing the second and subsequent times reloads the module from the system cache. Instead, you can:

- run ``del sys.modules['hexdump']`` and then ``import hexdump``;

- call ``importlib.reload(hexdump)``; or

- restart the REPL.

Remember that reloading the module won't redefine any existing classes or instances you created from the old module, they will continue to reference the old module code until they are destroyed and recreated. So the last option (restarting the REPL) is usually the most effective. But with care, reload(hexdump) should do the trick.